python中字典如何按照value排序？

dict= {'a':1,'b':4,'c':2}

sorted(dict.items(),key = lambda x:x[1],reverse = True)

test_data_6=sorted(dict_data.items(),key=operator.itemgetter(1))

test_data_7=sorted(dict_data.items(),key=operator.itemgetter(1),reverse=True)

print(test_data_6) #[(8, 2), (10, 5), (7, 6), (6, 9), (3, 11)]

print(test_data_7) #[(3, 11), (6, 9), (7, 6), (10, 5), (8, 2)]

f = zip(d.keys(), d.values())

c = sorted(f)

print(c)